Mid-bass horn (easy to build)

[carpenter]

I've designed a great sounding mid-bass horn that's super easy to fabricate. I'm using a JBL 2240 18" driver, but have simulated (Hornresp) inexpensive B&C 18PS76 18" woofers that perform almost as well and cost under $200.00 apiece at Parts Express. I've posted info on my web page: inlowsound.com
Check out the Diy 80 hz mid-bass horn page.

[Zen Mod]

[carpenter]

Originally Posted by Zen Mod

Choky, you are the sweetest of the bunch

[JoshK]

Very cool! I am in the design stages for building a ~65hz midbass horn. I like seeing what others have done.

My ony concern is that the horn is a bit small (theoretically) for 80hz loading. Have you measured the impedance sweep?

From your plans, I gather your horn is roughly 32" long and has a circumference of nearly 96". Typical horn math philosophy suggests that the mouth circumference be one wavelength and the depth is > 1/4 wavelength. The wl of 80hz is 168". 96"/168" = .57 wavelength and the depth is ~1/5 wl.

I don't know how critical this is, just raising the standard questions.

[revintage]

There will be no problem with this 80(75Hz) horn. If you look at Edgars 80Hz it is only ca 60cm long and Am ca 3000cm2 and that one works OK.

Here we have over 80cm length and almost 5000cm2 Am. The only concern could be the rather high Mms. But the sims says something else.

Carpenter,

If you sim the horn like an Exp(no big difference) you will be able to leave the less relevant "constant directivity" and instead use directivity, on- or off-axis at choosen angle. I normally use 20 degrees for lower placed midhorns.

Your horns will fall just a little bit more than the Exp.

[carpenter]

Thanks for the input, guys.

This horn hits the drum passages with power to spare and sounds excellent while performing its job. I hear very little distortion compared to the exponential horns I used to build. Hornresp has been such a blessing -- what an amazing age we live in.

I've been asked to supply more information on my Diy 80hz horn page and will do so in the near future.

[JoshK]

FWIW, I am not critizing the choices made. These are certainly more reasonably sized then full mouth horns. My question/concern only has to do with what effects do the compromises have. I simply have no experience here and would like to ponder the issue.

[carpenter]

Originally Posted by JoshK

FWIW, I am not critizing the choices made. These are certainly more reasonably sized then full mouth horns. My question/concern only has to do with what effects do the compromises have. I simply have no experience here and would like to ponder the issue.

If you have an excellent subwoofer section, then you will find this mid bass horn is just the right size. In fact, I designed it to tamp down the sub bass -- it always felt like a tank down low in that my system had gobs of power, but felt clunky. This horn gives plenty of snap and punch and takes my system from very good to excellent in the performance dept. It's no longer a Cadillac, but more of a Formula 1.

Edit: the horn is allowed a smaller mouth because of the plane it was designed to perform in. It gets the back wall and the floor, and perhaps even a bit of the side wall for the very bottom end of its spectrum. Believe me, there's more bass there than I expected, and because of the light cone/powerful motor in this 18" driver, the power is out of this world.

[kipman725]

very cool, had a good read of your site. Particularly liked the fabrication instructions for that huge paper horn, what kind of efficiency do you get from it?

[Altec Best]

Nice site ! I also like the Altec A-7 you have tested.Should try it with a 515B or a 416B Talk about efficient. For the mid bass go with the 515 if you want to go a little lower than the 416. Very Nice work !